Saudi Arabia is set to shatter the record for the tallest building in the world, with a slender, asymmetrical spire that'll rise at least 3,280 feet in the air. That's more than twice the size of the Willis Tower, the tallest building in the United States, and 568 feet taller than the Burj Khalifa, the tallest building in the world.

The $1.2 billion Kingdom Tower will be built in north Jeddah, the major urban center of western Saudi and an historic gateway to Mecca just off the shores of the Red Sea. The building, by Chicago-based Adrian Smith + Gordon Gill Architecture (Smith also designed the Burj Khalifa while at SOM), pairs new developments in skyscraper technology with a sleek, "three-petal" form inspired by the folded fronts of young desert plant growth. "The way the fronds sprout upward from the ground as a single form, then start separating from each other at the top, is an analogy of new growth fused with technology," Gill says.

The tower's got a slick, aerodynamic shape with tapering wings that'll help slash structural loading caused by wind. A high-performance facade is expected to drastically reduce energy consumption, and notches in each of the skyscraper's three "petals" will create pockets of shade, shielding occupants from the harsh desert sun and providing outdoor terraces with views of Jeddah and the Red Sea. Kingdom Tower will include a Four Seasons hotel and apartments, luxury condominiums, and Class A offices spread over roughly 3.5-million square feet. It'll also have a sky terrace on the 157th floor (the 157th floor!) and the highest observatory in the world.

Kingdom Tower is the linchpin of a larger, $20 billion waterfront development venture for Jeddah — part of the Saudi monarchy's ambitious efforts to diversify its economy beyond crude oil. (Financing for the Kingdom Tower results from a deal between the investment firm of Saudi billionaire Prince Alwaleed bin Talal and the Saudi Binladin Group, a construction conglomerate founded by the father of you know who.) The proposed Kingdom Tower Waterfront District — the master plan of which is also designed by Adrian Smith + Gordon Gill — will include residential and commercial buildings, a shopping mall, outdoor spaces, and other amenities.